GB378385A - Improved manufacture of wooden sheets - Google Patents

Abstract

378,385. Treating wood; compound sheet materials. HERZOG, R. O., 18, Kaiser- Wilhelmstrasse, Steglitz, and BURGENI, A., 54, Unter den Eichen, Lichterfelde- Went, both in Berlin. May 4, 1931, No. 13155. [Class 140.] Wood sheets of leather-like softness and pliability are obtained by chemically loosening and swelling the wood structure until it becomes pliable and impregnating it with substances for maintaining the swollen and pliable condition. The pliability may be produced by any process for the production of cellulose, alkaline, acid or oxidizing, provided it is not carried too far, viz. to the production of hydrocellulose. Lime wood veneers are, for example, treated for six hours with a cold 4 per cent caustic soda solution, or for three hours at 75‹ C. with 0.1 per cent solution, and maple, oak, pine, and other woods with a cold 6-16 per cent solution for two hours. The wood may be bleached, for example, with sodium hypochlorite or 2 per cent oxalic or sulphuric acid and then is treated with water-soluble substances of low vapour pressure such as glycerine, monoacetin, and lactates to make the pliability permanent. Liquid, dissolved or emulsified hydrocarbons, fats, oils, soaps, and emulsifying agents such as sulpho- and oxy-fatty acids and their derivatives, turkey-red oil, monopole soap, &c. may simultaneously be added to enhance the pliability. Soluble organic compounds such as cane, invert or starch sugar, urea, or soluble salts such as sodium chloride or ammonium sulphate or other easily soluble substances may also be added as fillers to prevent shrinkage. To strengthen the material, elastic film forming colloids such as rubber, polyvinyl acetate, polyacrylic acid, glue, gelatine, and cellulose esters may be added. The wood may be soaked with vinyl acetate, acrylic acid, and other condensable or polymerizable substances, to which plastifiers may be added, which are then condensed or polymerized to give the colloids. The colloids can also be applied by brushing, dipping, or spraying as a surface (oating only. The wood may be given, before, luring, or after the process, a mechanical working in calenders or presses to increase the pliability, and may be rolled to give a uniform product. The thin wood sheets may be combined with a support of felted fibres, fabrics, metal cloth or foil by means of an adhesive which may be the same as the protective coating, e.g. polyvinyl acetate and cellulose esters. The threads of the warp and weft of the fabric may be of different strengths to emphasize the structure of the wood. The compound sheets can be used for roll curtains, as furniture, upholstering, wall paper, carpets, &c., and can be cut into strips for making basketwork. Specifications 21190/95, [Class 145, Wood &c.], and 25273/09, [Class 140, Waterproof &c. fabrics], are referred to.